This laboratory and colleagues demonstrated that Group 1 CD1a, b and c antigen presenting molecules present lipid and glycolipid microbial antigens to T cells. In order to determine the nature of the immune response to M. tb antigens following virulent infection, we have established a guinea pig model of aerosol infection with the virulent H37Rv strain of M. tb. We cloned the guinea pig CD1 genes, expressed them in transfectant cells, and identified anti-guinea pig CD1 specific mAb that allow characterization of CD1 immune responses in guinea pigs. Following infection in guinea pigs, we will determine the pattern of expression of CD1 in lymphoid organs and relevant sites of infection. We will identify the immunodominant M. tb lipid antigens that activate T cell responses and the CD1 isoforms that mediate their presentation. These data will provide valuable information for the testing of immunodominant lipid fractions as vaccine candidates. We hypothesize that antigen presentation by CD1 will elicit T cells that add a distinct component of cellular immunity against microbes that is missing in vaccine formulations that contain or encode only protein antigens. Therefore, we propose to combine immunodominant CD1 presented lipid antigens with MHC presented protein antigens in a combination subunit vaccine to elicit a composite immune response. Together, these studies will move forward our understanding of the basic biology of CD1 antigen presentation during microbial infection in vivo with applications of this emerging biology to vaccine development.